The goal of this project is to develop a nosology of psychopathology for children 2 to 4 years of age. Two observational instruments (see reports Z01MH 0217-03,04, and 05) were developed that allow for reliable and systematic recording of the child's behavior. One instrument is used for a semi-structured play interview with a psychiatrist, when mother is not present. The second instrument is used to observe the child in interaction with mother. Children were rated on degree of risk for the later development of psychopathology based on their performance in the two settings. From a case by case analysis of the 16 children who were rated as being at high risk in both settings, a nosology for describing current worrisome behavior has been developed. The behavior was evaluated along four dimensions: quality of child's relationship with mother child's dominant mood, child's ability to regulate his mood, child's mastery as revealed in play. This yielded four syndromes of deviant behavior. Syndrome D: the relationship to mother is detached, dominant mood is bland, mood expression is overcontrolled, and play is minimal. Syndrome S: the relationship to mother is physically clingy, yet emotionally isolated, the dominant mood is sadness, moods are poorly regulated, and play is absent. Syndrome A: the relationship to mother is angry, the dominant mood is anger, there is excessive expression of negative moods, and play is minimal. Syndrome SD: the relationship to mother is variable ranging from moments of warmth to excessive anger. The dominant mood is anger. When under the direct supervision of an adult child can control the expression of his anger and engage in productive play. The children are structure dependent. When not under the direct supervision of an adult, the children lose control of their anger and their play becomes dysfunctional.